Open Access. Powered by Scholars. Published by Universities.®

Stars, Interstellar Medium and the Galaxy Commons™

Open Access. Powered by Scholars. Published by Universities.®

Discipline
Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 1261 - 1290 of 1375

Full-Text Articles in Stars, Interstellar Medium and the Galaxy

Rotation Periods Of Open Cluster Stars, Ii, Charles F. Prosser, Matthew D. Shetrone, Ettore Marilli, Santo Catalano, Scott D. Williams, Dana E. Backman, Bentley D. Laaksonen, Vikram Adige, Laurence A. Marschall, John R. Stauffer Dec 1993

Rotation Periods Of Open Cluster Stars, Ii, Charles F. Prosser, Matthew D. Shetrone, Ettore Marilli, Santo Catalano, Scott D. Williams, Dana E. Backman, Bentley D. Laaksonen, Vikram Adige, Laurence A. Marschall, John R. Stauffer

Physics and Astronomy Faculty Publications

We present the results from a photometric monitoring program of 21 stars observed during 1992 in the Pleiades and Alpha Persei open clusters. Period determinations for 16 stars are given, 13 of which are the first periods reported for these stars. Brightness variations for an additional five cluster stars are also given. One K dwarf member of the a Per cluster is observed to have a period of rotation of only 4.39 hr, perhaps the shortest period currently known among BY Draconis variables. The individual photometric measurements have been deposited with the NSSDC. Combining current X-ray flux determinations with known …

Go to article

Spot On Rs Cvn From Spectroscopy And Photometry, Joel A. Eaton, Gregory W. Henry, Coretta Bell, Albert Okorogu Sep 1993

Spot On Rs Cvn From Spectroscopy And Photometry, Joel A. Eaton, Gregory W. Henry, Coretta Bell, Albert Okorogu

Information Systems and Engineering Management Research Publications

We have used contemporaneous spectra and V light curves to form spot models for RS CVn in 1991 and 1992. More than two spots are needed to fit all the properties of the observations. In fact, moderately small spots (22 x 28 deg in latitude and longitude) having only a slight effect on the rotational light curve were eclipsed in both years, and we find that a collection of 6-8 such moderate spots is required to fit the line profiles in each year. These groups of spots also account naturally for a difference in level of light between the two …

Go to article

The Spectroscopic Orbit Of Gamma Geminorum And A Search For Its Secondary, Francis C. Fekel, Jocelyn Tomkin Sep 1993

The Spectroscopic Orbit Of Gamma Geminorum And A Search For Its Secondary, Francis C. Fekel, Jocelyn Tomkin

Information Systems and Engineering Management Research Publications

New spectroscopic observations of Gamma Geminorum, a bright, 'normal' A1 IV star have resulted in an improved spectroscopic orbit. The orbital period is 12.632 +/- 0.002 yr, the eccentricity is 0.893 +/-0.002, and the orbital parallax is 0.0291 +/-0.0024 arcsec, or a distance of 34 pc. We determine a v sin i of 8 +/-1 km/s for the A star, which confirms that it is a slow rotator. Near-infrared spectroscopic observations at 8806 A, obtained through the brief nodal passage, have resulted in the probable detection of the secondary. The masses are 2.8 and 1.07 solar mass and the Delta …

Go to article

Radial-Velocity And Light Variations Of Ir Cephei, Laurence A. Marschall, Michael A. Seeds, Robert J. Davis Sep 1993

Radial-Velocity And Light Variations Of Ir Cephei, Laurence A. Marschall, Michael A. Seeds, Robert J. Davis

Physics and Astronomy Faculty Publications

Radical-velocity observations of the short-period Cepheid, IR Cephei, have been used to derive a complete radial-velocity versus phase curve for the variable, to investigate the presence of a possible binary companion, and to address the question of its membership in the Cepheus OB2 association. The observations are consistent with the absence of a close binary companion and shed doubt on its membership in the association. Photoelectric observations made with the Phoenix 10 Automated Photometric Telescope confirm the single nature of the star. We present simulations to show the effects of an equiluminous companion on the light curve of a Cepheid, …

Go to article

Ccd Photometry Of The Old Open Cluster M67, Kent A. Montgomery, Laurence A. Marschall, Kenneth A. Janes Jul 1993

Ccd Photometry Of The Old Open Cluster M67, Kent A. Montgomery, Laurence A. Marschall, Kenneth A. Janes

Physics and Astronomy Faculty Publications

We present a CCD photometric survey of the central one-half degree of the old open cluster, M67, in U, B, V, and I colors to magnitude V=20. Extensive comparison of our photometry with other published datasets shows excellent agreement, indicating that CCD photometry is capable of producing a uniform set of measurements consistent with the photometric system defined primarily by the Landolt standard sequence. The color-magnitude diagram of the cluster shows a well-defined main sequence extending at least to the limit of the photometry at Mv=10.55 and a substantial binary sequence. At least 38% of cluster stars are …

Go to article

Chromospherically Active Stars. X. Spectroscopy And Photometry Of Hd 212280, Francis C. Fekel, Jared C. Browning, Gregory W. Henry, Mary D. Morton, Douglas S. Hall Jun 1993

Chromospherically Active Stars. X. Spectroscopy And Photometry Of Hd 212280, Francis C. Fekel, Jared C. Browning, Gregory W. Henry, Mary D. Morton, Douglas S. Hall

Information Systems and Engineering Management Research Publications

The system HD 212280 is a chromospherically active double lined spectroscopic binary with an orbital period of 45.284 days and an eccentricity of 0.50. The spectrum is composite with spectral types of G8 IV and F5-8 V for the components. An estimated inclination of 78 +/- 8 deg results in masses of 1.7 and 1.4 solar mass for the G subgiant and mid-F star, respectively. The distance to the system is estimated to be 112 pc. Photometric observations obtained between 1987 November and 1992 June reveal that HD 212280 is a newly identified variable star with a V amplitude of …

Go to article

Photometric And Spectroscopic Observations Of Sn 1990e In Ngc 1035: Observational Constraints For Models Of Type Ii Supernovae, Brian P. Schmidt, Robert P. Kirshner, Rudolph Schild, Bruno Leibundgut, David Jeffery, S. P. Willner, Reynier Peletier, Ann I. Zabludoff, Mark M. Phillips, Nicholas B. Suntzeff, Mario Hamuy, Lisa A. Wells, Chris Smith, Jack A. Baldwin, W. G. Weller, M. Navarette, L. Gonzalez, Alexei V. Filippenko, Joseph C. Shields, Charles C. Steidel, Saul Perlmutter, Carlton R. Pennypacker, Craig K. Smith, Alain C. Porter, Todd A. Boroson, Raylee Stathakis, Russell Cannon, J. Peters, E. Horine, Kenneth C. Freeman, Donna S. Womble, Remington P.S. Stone, Laurence A. Marschall, Andrew C. Phillips, A. Saha, Howard E. Bond Jun 1993

Photometric And Spectroscopic Observations Of Sn 1990e In Ngc 1035: Observational Constraints For Models Of Type Ii Supernovae, Brian P. Schmidt, Robert P. Kirshner, Rudolph Schild, Bruno Leibundgut, David Jeffery, S. P. Willner, Reynier Peletier, Ann I. Zabludoff, Mark M. Phillips, Nicholas B. Suntzeff, Mario Hamuy, Lisa A. Wells, Chris Smith, Jack A. Baldwin, W. G. Weller, M. Navarette, L. Gonzalez, Alexei V. Filippenko, Joseph C. Shields, Charles C. Steidel, Saul Perlmutter, Carlton R. Pennypacker, Craig K. Smith, Alain C. Porter, Todd A. Boroson, Raylee Stathakis, Russell Cannon, J. Peters, E. Horine, Kenneth C. Freeman, Donna S. Womble, Remington P.S. Stone, Laurence A. Marschall, Andrew C. Phillips, A. Saha, Howard E. Bond

Physics and Astronomy Faculty Publications

We present 126 photometric and 30 spectral observation of SN 1990E spanning from 12 days before B maximum to 600 days past discovery. These observations show that SN 1990E was of type II-P, displaying hydrogen in its spectrum, and the characteristic plateau in its light curve. SN 1990E is one of the few SNe II which has been well observed before maximum light, and we present evidence that this SN was discovered very soon after its explosion. In the earliest spectra we identify, for the first time, several N II lines. We present a new technique for measuring extinction to …

Go to article

Observations Of The Ca Ii Infrared Triplet In Chromospherically Active Single And Binary Stars, Robert C. Dempsey, Bernard W. Bopp, Gregory W. Henry, Douglas S. Hall May 1993

Observations Of The Ca Ii Infrared Triplet In Chromospherically Active Single And Binary Stars, Robert C. Dempsey, Bernard W. Bopp, Gregory W. Henry, Douglas S. Hall

Information Systems and Engineering Management Research Publications

Spectroscopic observations of the Ca II infrared triplet (8498, 8542, 8662 A) have been obtained for 45 stars which are known or suspected to be chromospherically active. The sample includes both single and binary stars of spectral types from F2 to M5 spanning luminosity classes III, IV, and V. Several different types of activity diagnostics were measured, and their relative merits are discussed. Dependence of chromospheric emission upon rotation period, luminosity, temperature, and duplicity are analyzed. Synchronous binaries show a slight trend of increased emission with decreasing period while the asynchronous binaries show abnormally high activity levels for their rotation …

Go to article

The Triple Symbiotic System Ch Cygni, Kenneth H. Hinkle, Francis C. Fekel, Diana S. Johnson, Werner W.G. Scharlach Mar 1993

The Triple Symbiotic System Ch Cygni, Kenneth H. Hinkle, Francis C. Fekel, Diana S. Johnson, Werner W.G. Scharlach

Information Systems and Engineering Management Research Publications

Analysis of high-resolution IR spectra of CH Cygni shows that the star is a triple system with a short period orbit of just over 2 yrs. The period ratio of seven for CH Cyg is the smallest known for a triple system. The symbiotic pair is the short-period system. An eccentric and a circular orbit solution are determined for the short-period pair, and the circular orbit solution is found to be more appropriate. The observed eccentricity appears to be due to phase-dependent line asymmetries resulting from the irradiation of the M giant by the white dwarf. The system does not …

Go to article

Lithium And Rapid Rotation In Chromospherically Active Single Giants, Francis C. Fekel, Suchitra C. Balachandran Feb 1993

Lithium And Rapid Rotation In Chromospherically Active Single Giants, Francis C. Fekel, Suchitra C. Balachandran

Information Systems and Engineering Management Research Publications

The rotational velocities presently obtained via spectroscopic observations of a group of moderately rapidly rotating, chomospherically active single giants indicate that Gray's (1989) rotostat hypothesis requires modification. Their rapid rotation appears to be due to high Li abundances, and results in increased chromospheric activity. A scenario is projected in which the surface convection zone reaches the rapidly rotating core just as a star begins its first ascent of the giant branch, and dredges both high angular momentum material and freshly synthesized Li to the surface.

Go to article

Extended Variability Of The Symbiotic Star Ag Draconis, Menas Kafatos, S. R. Meier Jan 1993

Extended Variability Of The Symbiotic Star Ag Draconis, Menas Kafatos, S. R. Meier

Mathematics, Physics, and Computer Science Faculty Articles and Research

We have analyzed the complete set of available IUE (International Ultraviolet Explorer) spectra for the symbiotic star AG Draconis covering the period from 1979 to 1989. All absolute line fluxes and wavelengths have been obtained for the prominent emission lines in the λλ1200-3200 wavelength range. These spectra contain observations which were taken before, during and after the two extended outbursts which occurred on 1980 November to 1981 November and 1985 February to 1986 January. These two outburst events have two maxima that are separated by ~1600 days, a time scale not known to be associated with the star, but which …

Go to article

Oscillator Strengths Of The Si Ii 181 Nanometer Resonance Multiplet, Scott D. Bergeson, J. E. Lawler Jan 1993

Oscillator Strengths Of The Si Ii 181 Nanometer Resonance Multiplet, Scott D. Bergeson, J. E. Lawler

Faculty Publications

We report Si II experimental log (gf)-values of –2.38(4) for the 180.801 nm line, of –2.18(4) for the 181.693 nm line, and of –3.29(5) for the 181.745 nm line, where the number in parenthesis is the uncertainty in the last digit. The overall uncertainties (~10%) include the 1 σ random uncertainty (~6%) and an estimate of the systematic uncertainty. The oscillator strengths are determined by combining branching fractions and radiative lifetimes. The branching fractions are measured using standard spectroradiometry on an optically thin source; the radiative lifetimes are measured using time-resolved laser-induced fluorescence.

Go to article

Radiative Lifetimes, Branching Ratios, And Absolute Transition Probabilities In Cr Ii And Zn Ii, Scott D. Bergeson, J. E. Lawler Jan 1993

Radiative Lifetimes, Branching Ratios, And Absolute Transition Probabilities In Cr Ii And Zn Ii, Scott D. Bergeson, J. E. Lawler

Faculty Publications

New absolute atomic transition probability measurements are reported for 12 transitions in Cr II and two transitions in Zn II. These transition probabilities are determined by combining branching ratios measured by classical techniques and radiative lifetimes measured by time-resolved laser-induced fluorescence. The measurements are compared with branching fractions, radiative lifetimes, and transition probabilities in the literature. The 206 nm resonance multiplets in Cr II and Zn II are included in this work. These multiplets are very useful in determining the distribution of the elements in the gas versus grain phases in the interstellar medium.

Go to article

Two New Spotted Variables-Hd 191262 And Hd 191011, Douglas S. Hall, Gregory W. Henry Nov 1992

Two New Spotted Variables-Hd 191262 And Hd 191011, Douglas S. Hall, Gregory W. Henry

Information Systems and Engineering Management Research Publications

New 1988-1990 photometry in V and B with a 16 inch automatic telescope shows that both HD 191262, a previously known chromospherically active binary, and its comparison star HD 191011 are variable, with starspots judged to be the mechanism in both. In HD 191262 and 191011, respectively, spot rotation periods of 5d.4 < P < 5d.7 and 1 7d.4 < P < 23d.0 were found and differential rotation coefficients of k=0.054 and 0.28 were estimated. HD 191011, shown to be a KS giant about 475 parsecs away, had eight different spots present during the 2.5 years of observation.

Go to article

Galactic Structure From Faint Stromgren Photometry: The Catalog Of Observations, Ted A. Von Hippel Nov 1992

Galactic Structure From Faint Stromgren Photometry: The Catalog Of Observations, Ted A. Von Hippel

Publications

We have initiated the faint photometric survey in the Stromgren system covering about 1 square degree and including 1238 objects in order to develop samples which best probe the thick disk population. The catalog of observations are presented here. They were acquired without kinematic or metallicity biases and are complete to V=17.3-18.5, depending on the field, for 810 early to relatively late type stars. Photometric metallicities were derived for 508 stars and indicate a metal-poor stellar population, consistent with a mixture of thick disk and halo stars. While the Stromgren u-band was not part of the survey, follow-up u-band observations …

Go to article

Line Profile Asymmetries In Chromospherically Active Stars, Robert C. Dempsey, Bernard W. Bopp, Klaus G. Strassmeier, Arno F. Granados, Gregory W. Henry, Douglas S. Hall Jun 1992

Line Profile Asymmetries In Chromospherically Active Stars, Robert C. Dempsey, Bernard W. Bopp, Klaus G. Strassmeier, Arno F. Granados, Gregory W. Henry, Douglas S. Hall

Information Systems and Engineering Management Research Publications

A powerful, new probe of chromospheric activity, cross-correlation, has been developed and applied to a variety of stars. In this particular application, an entire CCD spectrum of an active star is correlated with the spectrum of a narrow-line, inactive star of similar spectral type and luminosity class. Using a number of strong lines in this manner enables the detection of absorption profile asymmetries at moderate resolution (lambda/Delta lambda about 40,000) and S/N 150:1. This technique has been applied to 14 systems mostly RS CVn's, with 10 not greater than nu sin i not greater than 50 km/s and P not …

Go to article

Speckle And Spectroscopic Orbits Of The Early A-Type Triple System In Virginis, William I. Hartkopf, Harold A. Mcalister, Xinxing Yang, Francis C. Fekel Jun 1992

Speckle And Spectroscopic Orbits Of The Early A-Type Triple System In Virginis, William I. Hartkopf, Harold A. Mcalister, Xinxing Yang, Francis C. Fekel

Information Systems and Engineering Management Research Publications

Eta Virginis is a bright (V = 3.89) triple system of composite spectral type A2 IV that has been observed for over a dozen years with both spectroscopy and speckle interferometry. Analysis of the speckle observations results in a long period of 13.1 yr. This period is also detected in residuals from the spectroscopic observations of the 71.7919 day short-period orbit. Elements of the long-period orbit were determined separately using the observations of both techniques. The more accurate elements from the speckle solution have been assumed in a simultaneous spectroscopic determination of the short- and long-period orbital elements. The magnitude …

Go to article

Hr 266=Ads 784: An Early Type Spectroscopic, Speckle Astrometric Multiple System, Warren A. Cole, Francis C. Fekel, William I. Hartkopf, Harold A. Mcalister, Jocelyn Tomkin Apr 1992

Hr 266=Ads 784: An Early Type Spectroscopic, Speckle Astrometric Multiple System, Warren A. Cole, Francis C. Fekel, William I. Hartkopf, Harold A. Mcalister, Jocelyn Tomkin

Information Systems and Engineering Management Research Publications

The detection and nature of a 'speckle astrometric' system are reported with attention given to alternative interpretations of the system components. The HR 226 = ADS 784 system is described as a short-period binary (with a period of 4.241148 +/- 0.000008 d) orbiting an unseen companion (with a period of 1769 +/- 10 d), and the triple's visual orbit is 83.10 +/- 0.20 yr. The elements of the various orbits taken from spectroscopic data are employed to develop the model scenarios. The masses and spectral types of the components are developed and used to calculate the inclinations of the short-, …

Go to article

Fe Ii Fluorescence And Anomalous C Iv Doublet Intensities In Symbiotic Novae, A. G. Michalitsianos, Menas Kafatos, S. R. Meier Jan 1992

Fe Ii Fluorescence And Anomalous C Iv Doublet Intensities In Symbiotic Novae, A. G. Michalitsianos, Menas Kafatos, S. R. Meier

Mathematics, Physics, and Computer Science Faculty Articles and Research

Symbiotic stars frequently exhibit anomalous C IV λλ1548.2, 1550.8 doublet flux ratios, in which the intensity ratio of the blue and red doublet members is below the optically thick limit of unity. Three symbiotic stars (RR Tel, RX Pup, and AG Peg) have been investigated in detail with high-resolution spectra obtained from the International Ultraviolet Explorer (IUE) archives. We have examined the deficit of C IV λ1548.2 emission relative to λ1550.8 in context with the fluorescent pumping of the Fe II multiplet (45.01) λ1548.204 by the C IV λ1548.2 line. In RR Tel the C IV λ1548.2 flux is correlated …

Go to article

The 11 Year History Of Starspots On V1149 Ori=Hd 37824, Douglas S. Hall, Francis C. Fekel, Gregory W. Henry, William S. Barksdale Nov 1991

The 11 Year History Of Starspots On V1149 Ori=Hd 37824, Douglas S. Hall, Francis C. Fekel, Gregory W. Henry, William S. Barksdale

Information Systems and Engineering Management Research Publications

All available radial-velocity measures, published and unpublished, yield an improved period and a new (assumed circular) solution. The period is 53.58 d +/- 0.02 d, and conjunction (K1 giant in front) was at 2 444 325.93 +/- 0.12 d. Eleven years of V-band photometry, published and unpublished, between 1978-1979 and 1989-1990 are analyzed. Eighteen data groups are fit with a two-spot light-curve-modeling technique. Six spots existing sometime during the 11 years are identified, and the 4-percent range of their rotation periods is used to estimate a differential rotation coefficient of k = 0.08 +/- 0.02. Observed lifetimes of those six …

Go to article

Chromospherically Active Stars. Ix. Hd 33798 = V390 Aurigae: A Lithium-Rich Rapidly Rotating Single Giant., Francis C. Fekel, Laurence A. Marschall Oct 1991

Chromospherically Active Stars. Ix. Hd 33798 = V390 Aurigae: A Lithium-Rich Rapidly Rotating Single Giant., Francis C. Fekel, Laurence A. Marschall

Information Systems and Engineering Management Research Publications

Results are presented of spectroscopic observations of HD 33798 obtained to determine if this star is a short-period binary and to examine its evolutionary status. Analysis of 40 radial velocities indicates no periodic velocity variations, suggesting that the star is single, so its rapid rotation is highly unusual. This rotation is inconsistent with the rotational brake hypothesis advanced by Gray (1989). It is proposed that HD 33798 is in a post-main-sequence phase of evolution. Its space motion is similar to FK Com, suggesting that it is a coalesced binary in the process of spinning down. Scenarios are presented to explain …

Go to article

Chromospherically Active Stars Ix Hd 33798 = V390 Aurigae: A Lithium-Rich Rapidly Rotating Single Giant, Francis C. Fekel, Laurence A. Marschall Oct 1991

Chromospherically Active Stars Ix Hd 33798 = V390 Aurigae: A Lithium-Rich Rapidly Rotating Single Giant, Francis C. Fekel, Laurence A. Marschall

Physics and Astronomy Faculty Publications

HD 33798 is a chromospherically active, rapidly rotating, lithium-rich, late-type giant. Analysis of 40 radial velocities indicates no periodic velocity variations, suggesting that the star is single, so its rapid rotation (v sin i = 29 km s-1) is highly unusual. Such rotation is inconsistent with the rotational brake hypothesis of Gray [ApJ, 262, 682 (1982); 347, 1021 (1989)] and the results of Rutten & Pylyser [A&A, 191, 227 (1988)]. Although there are many similarities to the supposed pre-main-sequence star HDE 283572, the lithium abundance and space motion of HD 33798 appears to be in a post-main-sequence phase of …

Go to article

Asteroseismology Of The Dov Star Pg 1159-035 With The Whole Earth Telescope, Donald E. Winget, R. Edward Nather, J. Christopher Clemens, Judith Provencal, Scot J. Kleinman, Paul A. Bradley, Matt A. Wood, Charles F. Claver, Marian L. Frueh, Albert D. Grauer, Butler P. Hine, Carl J. Hansen, Gilles Fontaine, Nicholas Achilleos, Dayal T. Wickramasinghe, T.M.K. Marar, S. Seetha, B. N. Ashoka, Darragh O'Donoghue, Brian Warner, Donald W. Kurtz, David A. Buckley, J. Brickhill, Gerard Vauclair, Noël Dolez, Michel Chevreton, Martin A. Barstow, Jan-Erik Solheim, Antonio Kanaan, Kepler De Souza Oliveira Filho, Gregory W. Henry, Steven D. Kawaler Sep 1991

Asteroseismology Of The Dov Star Pg 1159-035 With The Whole Earth Telescope, Donald E. Winget, R. Edward Nather, J. Christopher Clemens, Judith Provencal, Scot J. Kleinman, Paul A. Bradley, Matt A. Wood, Charles F. Claver, Marian L. Frueh, Albert D. Grauer, Butler P. Hine, Carl J. Hansen, Gilles Fontaine, Nicholas Achilleos, Dayal T. Wickramasinghe, T.M.K. Marar, S. Seetha, B. N. Ashoka, Darragh O'Donoghue, Brian Warner, Donald W. Kurtz, David A. Buckley, J. Brickhill, Gerard Vauclair, Noël Dolez, Michel Chevreton, Martin A. Barstow, Jan-Erik Solheim, Antonio Kanaan, Kepler De Souza Oliveira Filho, Gregory W. Henry, Steven D. Kawaler

Information Systems and Engineering Management Research Publications

We report the results from 264.1 hr of nearly continuous time-series photometry on the pulsating pre-white dwarf star (DOV) PG 1159-035. The high-resolution power spectrum of this data set is dominated by power in the range from roughly 1000 to 2600 μHz (1000 s to 385 s periods). This power is completely resolved into 125 individual frequencies; we have identified 101 of them with specific, quantized pulsation modes, and the rest are completely consistent with such modal assignment. The luminosity variations are therefore certainly the result of g-mode pulsations. Although the amplitudes of some of the peaks exhibit significant variations …

Go to article

Photometry Of The Chromospherically Active Binary Hd 197010, Laurence A. Marschall, Harold L. Nations, B. W. Taylor, T. L. Huard Jul 1991

Photometry Of The Chromospherically Active Binary Hd 197010, Laurence A. Marschall, Harold L. Nations, B. W. Taylor, T. L. Huard

Physics and Astronomy Faculty Publications

For the past several years we have been conducting a study of the spectroscopic and photometric characteristics of a sample X-ray emitting stars from the Einstein Observatory Medium Sensitivity Survey identified as probable binary systems by Fleming (1988) and Fleming, et al.(1989). One of these stars, HD 197010 ( = 1E2038.3-0046 = SAO 144692 = BD -1degree 4025) was discovered to be a short period eclipsing binary by Robb, et al.(1990). The ephemeris he presented was based on observations in 1989 and 1990, but only the 1990 observations included points at eclipse minimum. We report here on first results of …

Go to article

The Extraordinary 1989 December 14/15 Optical Flare Events On V711 Tauri, Gregory W. Henry, Douglas S. Hall May 1991

The Extraordinary 1989 December 14/15 Optical Flare Events On V711 Tauri, Gregory W. Henry, Douglas S. Hall

Information Systems and Engineering Management Research Publications

Photometry in B and V taken with the Vanderbilt Tennessee State 16 inch (41 cm) robotic telescope confirms the intense broad-band optical continuum flare activity reported by Chinese observers on the active chromosphere binary V711 Tau on December 14/15, 1989. Twelve hours after the flare reported from China, there occurred a separate and more intense flare with B and V amplitudes of 0.69 and 0.42 mag, respectively. These amplitudes correspond to peak flare luminosities of approximately 2 x 10 to the 33rd ergs/s in B and 1 x 10 to the 33rd ergs/s in V. The observed color of its …

Go to article

Chromospherically Active Stars. Viii. Hd 155683 = V972 Herculis: Observational Constraints On Evolutionary Theory, Francis C. Fekel Apr 1991

Chromospherically Active Stars. Viii. Hd 155683 = V972 Herculis: Observational Constraints On Evolutionary Theory, Francis C. Fekel

Information Systems and Engineering Management Research Publications

V792 Her is an eclipsing RS CVn binary with an orbital period of 27.54 days whose components have spectral types of K0 III and F2 IV. New spectroscopic observations combined with existing photometry have resulted in masses of 1.47 + or - 0.003 solar mass and 1.41 + or - 0.003 solar mass for the K giant and F star, respectively. Additional fundamental parameters are derived. Standard evolutionary models were specifically computed by VandenBerg (1990) for the two stars. The best fit occurs if the components are somewhat metal poor with Fe/H/ = - 0.46. Ages of about 2.3 x …

Go to article

Uv Observations Of The Cool Dbqa5 White Dwarf Lds 678a - Limits On The Atmospheric Composition, Pressure Shift, And Gravitational Redshift Derived From C I 2479, Terry D. Oswalt, Edward M. Sion, Gordon Hammond, Gerard Vauclair, James W. Liebert, Gary Wegner Jan 1991

Uv Observations Of The Cool Dbqa5 White Dwarf Lds 678a - Limits On The Atmospheric Composition, Pressure Shift, And Gravitational Redshift Derived From C I 2479, Terry D. Oswalt, Edward M. Sion, Gordon Hammond, Gerard Vauclair, James W. Liebert, Gary Wegner

Dartmouth Scholarship

A high-resolution ultraviolet spectrum of the helium-rich degenerate LDS 678A, obtained with the International Ultraviolet Explorer (IUE) satellite, is presented. LDS 678A is the coolest metallic line degenerate (DQ or DZ) yet observed with the IUE echelle. These observations provide a detailed line profile of the strong C I 2479 absorption line and equivalent width W2479 = 2.35 + or - 0.06 A from which theoretical profile fits yield a carbon abundance of log C/He = (-6.7 + or- 0.2). The presence of carbon in a He-rich atmosphere lends credence to the notion that LDS 678A is a transitional case …

Go to article

Simultaneous Light And Radial Velocity Curve Solutions For U Cephei, J. B. Rafert, N. L. Markworth Jan 1991

Simultaneous Light And Radial Velocity Curve Solutions For U Cephei, J. B. Rafert, N. L. Markworth

Faculty Publications

The light-curve synthesis approach of Wilson & Devinney has been used to solve simultaneously light and radial velocity curves of the Algol-type eclipsing binary star U Cephei. We have performed eight new differential corrections solutions using the photometric data of Markworth and the radial velocity data of Batten to obtain a consistent set of orbital and astrophysical parameters for the light and velocity curves of this famous system. We find U Cephei to be best modeled using the semidetached (mode 5) system geometry of the Wilson & Devinney program, with a primary rotating at about 5.2 times its synchronous rate, …

Go to article

Forbidden Lines Of Np^Q Ions. Ii. Line Intensities, J. P. Lynch, Menas Kafatos Jan 1991

Forbidden Lines Of Np^Q Ions. Ii. Line Intensities, J. P. Lynch, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

Ground state forbidden transitions of np^q ions of C, N, 0, Ne, Mg, Si, S, and Fe can provide important information on the state of cosmic ionized gases. Wavelengths of these lines are in the far- and near-UV visible and near- and far-IR regions of the spectrum. The line intensity ratios of particular transitions in q = 2, 4 ions can provide information on the temperature of the gas and in q = 3 ions information on the density of the gas. In the present work we have tabulated the line intensities of 95 transitions of these ions, which include …

Go to article

Ultraviolet And Optical Spectroscopy Of The R Aquarii Symmetrical Jet, J. M. Hollis, R. J. Oliverson, Menas Kafatos, A. G. Michalitsianos, R. M. Wagner Jan 1991

Ultraviolet And Optical Spectroscopy Of The R Aquarii Symmetrical Jet, J. M. Hollis, R. J. Oliverson, Menas Kafatos, A. G. Michalitsianos, R. M. Wagner

Mathematics, Physics, and Computer Science Faculty Articles and Research

The first ultraviolet spectrum of the southwest (SW) component of the symmetrical jet in the R Aquarii binary system has been obtained in the range 1200-2000 A with the International Ultraviolet Explorer (IUE). These results are compared to more encompassing spectra (1200-3200 A) of the central H II region taken at the same time and also similar spectra of the northeast (NE) jet component obtained 6 months earlier. Moreover, optical spectra of both the NE and SW jet components in the range 3400-9800 A were obtained within ~ 6 months and ~ 1 month, respectively, of the ultraviolet spectra. These …

Go to article

First Prev Next Last